Patent GB-754061-A (GB)
Title: Improvements in or relating to gas turbine plants
Inventor: MCDEVITT FRANK J
IPC: F02C9/28
Filed: 1954-08-19
Abstract: 754,061. Gas turbine plant. AKT.-GES. BROWN, BOVERI & CIE. Aug. 19, 1954, No. 24163/54. Class 110(3) In a gas turbine plant, combustion gases from a solid fuel furnace are conducted successively through a secondary combustion chamber and an air heater, compressed air is heated in the air heater and expanded through a gas turbine, high temperature air being supplied from the turbine exhaust to the furnace and the secondary combustion chamber, and a supplementary fluid fuel is burnt in the secondary combustion chamber at a rate which is responsive to variations of the temperature of the combustion gases entering the air heater. Municipal refuse of a relatively high moisture content is burnt in an incinerator furnace 30, the combustion gases passing into a secondary combustion chamber 38, where they may be further heated by a burner 48 which burns gas fuel or oil fuel. The gases then flow downwardly and under a hollow perforated wall 39 and through a perforated wall 41 of refractory brick which tends to render the flow more uniform. After passing through an air heater chamber 43, the gases are withdrawn by a fan 45 to a stack 46. Air compressed by compressors 1 and 7 passes by way of a conduit 8 to a tubular heat exchanger 10, where-it is heated by the combustion gases passing through chamber 38. The heated air passes by way of a conduit 12 to a turbine 13 which drives the compressors 1 and 7 and an electric generator 15. Part of the exhaust air from turbine 13 can pass through a conduit 17 to an intermediate point 47 of the chamber 43, under the control of a valve 19 which opens when the pressure in conduit 17 exceeds a predetermined value. The turbine exhaust air also passes through a conduit 18 and branch conduits 21 and 22 to the furnace 30 and the burner 48. Further branch conduits 26 and 63 lead turbine exhaust air to the hollow wall 39 and to a bustle pipe 62 which connects with ports in the wall of the furnace 30.. A damper 64 under the control of a thermostat 65 admits the air to the ports to dilute the combustion gases if the temperature of the latter tends to rise above a safe value. The air supplied through the hollow wall 39 dilutes the hot combustion gases with lower temperature air, and also tends to reduce stratification of the gases. A thermostat 55 controls a damper 23 to regulate the flow of air to the furnace 30. As the refuse burns out in the furnace 30, the thermostat 55 operates valves 49 and 51, increasing the supply of air and fuel respectively to the burner 48, whereby the combustion gas temperature is restored to the desired value. When a gate 36 is opened to permit recharging the furance 30 with refuse, a gate switch 66 is actuated to disconnect the thermostatic control from the damper 23, causing the latter to close; during recharging most of the combustion gases are supplied by the burner 48, under the control of thermostat 55. When refuse is not available, the heating is provided solely by the burner 48. In the event of overspeed due to loss of load on the generator 15, a governor 20 operates the damper 23 and valves 49, 51 to close down the supply of combustion gases, and at the same time opens a valve 75 to discharge a portion of the turbine exhaust air to atmosphere. In addition, solenoidcontrolled spring locks are actuated to cause a door 81 at each side of the chamber 40 to open to admit atmospheric air. These measures prevent overheating of the tubular air heater 10.